Electrical Modifications with Capacitive Elements
There's a stir in some quarters about "Dirty Electricity" and how it can harm you . . . However, Electricity was never "Dirty", and the moniker is simply a convenient coinage to imply that there is something "wrong" with it. What is wrong is that by exposure to it, the central nervous system may meet with electrical waveforms that have similarities to its own messaging, causing interference (pain, irritation, etc.). TENS instruments can do the same thing, but in a controlled fashion. How the interference gets to you is not usually noted, but in reality any system that allows Alternating Electric or Magnetic Fields (the carrier of the electrical "dirt") to occur in free space has the same "dirty" characteristics, even if it is an absolutely smooth waveform. So electrical "Dirt" is just another feature of the electrical system that has been in existence since its inception, and buying some gimmicky "filters" will not "harmonize" your living space from it / them.
With the advent of modern electrical devices, some are found to produce lots of electrical "jitter" (due to non-linear current consumption), or what we will refer to as "electrical noise", but more classically defined as ElectroMagnetic Interference (EMI).
This EMI is produced because anything that is not a smooth constantly changing waveform, such as the provided 60 Hz power, is composed of many Harmonics (or whole number multiples) of a fundamental frequency. To provide a fuller perspective, consider a common incandescent lamp. It will consume power smoothly and continuously as long as power is applied. Graphically it would look like the picture below left. In contrast, the consumption from a Compact Fluorescent bulb is similar to that below right.
Note that although the two waveforms in each graph are synchronized in time, their
vertical scales are different, and while the dark blue waveform is the Voltage supplied,
the light blue waveform is the Current allowed to flow by the device.
Then, taking a Spectrum Analysis of a Personal Computer power supply Current, whose waveform is very similar to that of a compact fluorescent bulb (above right), we get a display similar to that below.
Note that the spectrum is purposely only displayed to 2 KHz (2000 Hz), although
there are many more "bumps" in the higher frequencies. Interestingly, a common AM Radio
will detect a blanketing of its reception range anywhere near that power supply, indicating
that the frequencies produced (the "bumps") span up to and beyond 1 MHz (1,000,000 Hz).
The behavior of a capacitor, when exposed to a changing waveform, is to convert
the impressed Voltage to Current flow, determined by its electrical capacitance value.
Additionally, since no capacitor is perfect, such a conversion will add harmonics that
are solely generated by the capacitor. This Current is then impressed onto the Electrical
System Ground (ESG), which, albeit "grounded," will develop a Voltage directly
proportional to the amount of Current used (whether from capacitor filters alone or other
devices), due to the physics relationship described by Ohm's Law, that is now made
available through every cable within a residence.
So the capacitor filter, by whatever name, will Not make
your electricity cleaner, but dirtier.
To the right is a graph of Voltage measured on the ESG
compared to an Isolated Earth Ground, in a residence with several digital or otherwise
non-linear devices (note there is still a faint resemblance to 60 Hz) - your
guess as to how much "dirt" (harmonics) there is. While the general idea is that
placing one of these capacitive (dirty electricity) "filters" between the hot lead
and the Electrical System Ground (ESG) will "clean" up the hot lead, the idea is inherently
flawed because for it to work the ESG needs to be clean to begin with. Since these capacitors
allow energy to flow in both directions, an extremely "dirty" ESG is now going to "infect"
the hot lead with more "dirt" than there was to start with. If anyone tries to sell you a
"dirty electricity filter," and tells you it will "clean up" you electricity, and you buy it,
I have a bridge I'd like to sell you afterwards.
This EMI is impressed onto the supporting Power System. The power system, being what it is, allows circulating currents that should not exist, but do, because of wiring errors, redundant Neutral current paths, and system degradation over time. Since the typical electrical system is not subject to regular inspections, these problems can exist for years undetected, possibly causing biological damage, or possibly more immediate physical damage (such as death) due to maintenance on related systems that "unexpectedly" carry some of the shared neutral current.
The associated problems are typically 1) Neutral to Neutral wiring errors (with either Knob-and-tube, NM (Romex), or BX/MC), 2) Neutral to Ground wiring errors (with either knob-and-tube or BX/MC), or 3) normal shared Neutral paths between adjoining users (with any type of wiring).
Graphically, isolated detached errors exist as follows:
(with only
the Neutral (return) wire shown for clarity)
The magnetic field will exist and broadcast into free space regardless of the wire type. This shows a wiring error regarding lighting, which may be more common than for Power circuits. Nonetheless due to uncle Floyd and uncle Jack doing "creative wiring" over the years, any type (and mixture) of circuit can be involved.
Field Types
| Wiring Scheme | Normal Operation Emissions | Wiring Errors |
| Knob-and-Tube | wide-area Electric and Magnetic | wide-area Electric and Magnetic |
| NM / Romex | wide-area Electric | wide-area Electric and Magnetic |
| BX / MC | No emissions | wide-area magnetic |
| Redundant Neutrals | wide-area magnetic | wide-area magnetic |
If there is EMI associated with a cable, it will broadcast unimpeded into free space via other interconnected circuits as an Electric field component if the wiring type is either knob-and-tube or NM (Romex), even when those other circuits are not in use. If the circuits are in use, then the EMI will additionally become manifest as a Magnetic field component regardless of the wire type installed.
If any type of Capacitive filter is installed in an attempt to ameliorate the EMI, without the knowledge that there is a wiring error, then the field will exist as a Magnetic field component continuously regardless of the type of wire, AND as an Electric field component, depending on the wire type. That is because a capacitive filter will, by virtue of its physical characteristics, change a portion of the voltage pulsations (depending on frequency) impinging on it to current pulsations. So the process fundamentally involves a conversion, not an elimination.
Various capacitive filters are available. Some allow five amps per filter, some allow one amp per filter, and others allow a current based on whatever the individual capacitance value is, and how many are installed in the circuit. Thus the magnetic field presence can vary by the various factors just noted.
A characteristic of Alternating Power is that the power conveyance system (the transmission and distribution systems) and load systems are somewhat elastic, in that as voltage is applied the current does not flow immediately at the same instant, but a short time after (somewhere between 1 and 3 milliseconds). While this may seem like a small value, and it is, it can have a big financial impact on the producer and the user. The reason is that ideally both want the same amount of power produced as is being used, instantly and continuously. However, the small amount of time delay allows circulating currents known as Volt-Amperes Reactive (VARs) that can reduce system efficiency, or bring about a system collapse.
The time delay occurs because most user loads have Inductive elements. That is, the electrical qualities that foster the buildup of voltage but hamper the passage of current. With too much inductance, the voltage begins to drop because there is too much opposition to flow between the source and the user. One of the remedies is to add Capacitive elements. These devices foster the passage of current, but hamper the buildup of voltage. As capacitive elements compensate for the inductive elements, the conveyance system becomes more efficient, and the voltage goes back up.
Electricians have known about capacitive elements for a long time, as they are used to start motors, and are used to improve the efficiency of the power usage in large buildings. Even in a private residence of substantial size (5000 square feet, or 400+ Amps load service rating) capacitive elements may be added to improve the usage efficiency. With improved efficiency, and reduced time delay between voltage and current, the user is closer to consuming real power (watts), and not causing reactive power (VARs).
However, the insertion of Capacitive elements (capacitors, "Filters", etc.) within a home of average size is not warranted, as no improvement in power usage is realized, and owing to the built-in problems that have gone unnoticed for years, the situation will most likely be made worse than better. Considering that Electric and Magnetic components have biological impact capability, it is unconscionable for any individual or firm to market them without disclosing the very likely negative impact.
Granted, in the example shown it would be difficult to apply capacitive filters because the circuits are strictly for lighting, but mixed-use (power AND lighting) circuits exist often enough that any one circuit may have filter attachment capability (outlets).
The above sketch shows the interconnection between the electrical system ground, which can consist of any number of metallic structures in contact with the soil, and a metallic water pipe. Note that a magnetic field is depicted as existing regardless of whether the house shown is using any power (if it is located in a residential neighborhood where several homes are fed off the same power transformer). When the house shown begins to use power, it may add to, or subtract from the field, depending on which buss is flowing power at any moment, because the polarities may be opposite or alike.
The size of the field may be sufficient to engulf the entire house.
Adding any capacitive filter into any circuit, will have the effect of producing a continuous current flow which will be split between the electrical system neutral and the water pipe. If there is no other net (uncancelled) current in existence, one will be created. If there is a net current in existence, then the newly added one will either add to, or subtract from the field, possibly varying in direction and intensity from any moment in time to the next, depending on the polarity of the electric source (which will determine in which direction the current is generally flowing).
In any case, the current produced by insertion of a capacitor of any size is Non-Linear. That is, if you feed it 60 Hz (50 Hz) voltage, the current produced has many frequency components in addition to the original frequency. In light of this, application of a capacitor is not inconsequential, it makes the electricity, it is meant to clean up, "dirtier"!
When several homes are fed from the same power transformer as above, even if the water pipe and electrical service are located on the same side of the house (an ideal situation that could reduce the wide-area impact of split neutral currents), a magnetic field may exist from water piping in the street that could negate any of the considerations presented here, in that even neutral isolation would not accomplish a substantial reduction of the magnetic field presence.
While the insertion of any capacitive filter may have benefits in reducing some type of High Frequency (HF) EMI, their insertion needs to be carefully considered in light of any possible wiring errors, or even normal installation characteristics (as shown with the shared (or interconnected) neutrals) which could produce undesired Magnetic fields. As a general rule capacitive filter installation is NOT recommended without a thorough evaluation of the electrical system to identify and eliminate any wiring errors, and NOT recommended if the neutral current takes many divergent paths as shown in the house with the electrical service at one end of the house and the water pipe at the other end, and NOT recommended if there are any other options (like removing dimmer switches, replacing compact fluorescents or fluorescents in general with standard lamps, reducing the number of digital devices, etc.) available to eliminate the problem.